The Next Web speculates the reason Apple wants to buy Color is its patents:

Color said that it had six patents pending at the time of its funding, including its ‘elastic’ socialgraph and patents related to GPS location and battery saving. iOS developer DanielJalkut uncovered several patent applications that Color has filed for in the last couple of months that have names like “sharing content among a group of devices” and “user device group formation”.

All of those patents reference a provisional application filed back in March of 2012 on the multiple device method. It’s not much of a stretch to say these patents could be applied to Apple’s Photo Stream feature in iOS 6.

Maybe that's it. Or maybe it's that Color has hard-to-find, talented engineers and Apple doesn't mind spending a microscopic percentage of its huge cash pile to get them.

Also, Apple’s Senior Vice President Internet Software and Services Eddy Cue is said to be close with Nguyen.